The emotional response of many people to the news of Pluto’s “demotion” from planetary status points out a drastic misunderstanding of the nature of science. Science is the investigation of the natural world, a never-ending search for answers to current questions about how the universe works, as well as the search for new and better questions to ask. Sometimes discoveries are made and not completely understood at the time, leading to erroneous assumptions being made. Such was the case with Pluto in 1930. Clyde Tombaugh, a young amateur astronomer from Kansas, found the object after nearly a year of pouring over thousands of photographic plates, searching for the “missing planet” astronomer and (beneficiary of the observatory who had hired Tombaugh) Percival Lowell had been convinced existed. Pluto was the largest object Tombaugh found, and it was pronounced a planet before much was known about it.

Decades later, astronomers had learned more about Pluto’s properties, and it was obvious that it was not only very different from the four Earth-like rock and metal planets and the four Jupiter-like gas giant planets, but that it shared more in common with the myriad icy bodies in the outer solar system. The suggestion was made by those in the International Astronomical Union that Pluto be cross-classified as a planet and Kuiper Belt object, a member of the icy asteroid belt of sorts beyond the orbit of Neptune. The outcry from the general public was surprising, and rather alarming. Scientists admit their mistakes all the time, reclassifying objects, acknowledging that experiments and observations were mistaken, even the occasional embarrassing error in a theoretical calculation. All of this passes without a blink from Joe Q Public. Where was the outcry several years ago when the IAU extended the classification of stars to include the new classes L and T? Astronomy books had to be changed and students scrambled to create a new mnemonic device for the extended classification system (if anyone has a really good one for OBAFGKMLT, I’m all ears). When rabbits were reclassified from rodents to lagomorphs in the early 1900s, the Easter bunny did not suddenly change his trademark confectionary gifts.

Why is Pluto so different? Pluto’s proposed reclassification brought claims that textbooks would need to be changed, that children would have to learn new facts. Yes, they will, and they have, throughout the history of science! Astronomical discoveries happen at such a fast and furious rate these days that textbooks are out of date before their ink is even dry. The number of crossed-out sentences and hastily scribbled additions to the margins of my lecture notes drives home that point. When classes start in September, I will preface my comments on the first day of class as I normally do -- with the warning that 10% of what I will teach the students may eventually be proven wrong (a rather conservative estimate). Would the tax payers of Connecticut rather that I keep teaching the same astronomical concepts I taught when I began at CCSU in 1989? Would that better serve the students, lest they have to “learn new facts”? As members of a technological society, we have had to learn to deal with constant change, which is admittedly not always comfortable. I still have a box of eight-track tapes in my basement, for reasons that have nothing to do with science. Perhaps Pluto’s demotion hits some of us harder than others for a similar reason. At least there is one Pluto who will always retain his status as a “top dog” in the universe of Disney.

To those who would argue against reclassifying Pluto for emotional reasons, allow me to remind you of the story of the ugly ducking. Isn’t it is far better to let Pluto be a rather unconventional swan, rather than to continue dooming it to be the ugly duckling of the planetary community? If a young child is fascinated by Pluto, encourage them to be, but for Pluto’s distinctive properties, rather than based on some label it was erroneously given in 1930. If my pet rabbits were suddenly reclassified back to rodents, or to some other taxonomical grouping, it would not make me love them any less. Now if reclassifying them would make them suddenly stop thinking my laptop power cord was delicious, that would be a major scientific discovery!

--- Kristine Larsen, August 24, 2006